1. Field of the Invention
The present invention relates to a camera having a magnetic recording device capable of recording photographic information on a magnetic recording region provided on the film.
2. Description of the Related Art
For instance, in U.S. Pat. No. 5,006,873, a film is disclosed which is provided with magnetic recording regions in a plurality of tracks corresponding to the various frames on the film.
In U.S. Pat. No. 5,229,810, there is disclosed a camera which is capable of using a film as disclosed in U.S. Pat. No. 5,006,873. This camera is able to record information (hereinafter generally termed photographic information) such as for example the date of shooting each frame and/or the exposure values (stop number and shutter time) magnetically on the magnetic recording region of the film, simultaneously with winding on the film. This photographic information recorded on the film is read out by the developing laboratory when the film is being developed, and for example is overprinted upon the film in character form relating to the read out photographic information.
Further, in U.S. Pat. No. 4,832,275 for example, there is disclosed a film cartridge with which the film can be forwarded out from the cartridge and can be wound back into the cartridge by a film spool in the cartridge being rotated respectively in a forward or a backward rotational direction. If this type of cartridge is used, it is possible to shoot the frames on a film in the cartridge which has been loaded into the camera up to a certain intermediate frame, then temporarily to remove the film cartridge from the camera with the later frames after the intermediate frame remaining as non-exposed, and thereafter to load the film cartridge back into the camera again for shooting the later frames.
For instance, in U.S. Pat. No. 4,864,332, disclosed is a camera which can reliably prevent a double exposure. This camera is constructed such that information (hereinafter termed exposure completed information) showing that each frame has been exposed is magnetically recorded on a magnetic recording region of the film corresponding to this frame by a magnetic recording and playback head while the film is being wound on to the next frame after shooting this frame, and then when the film is reloaded into the camera the information on each magnetic recording region is read out by this magnetic recording and playback head so that exposure can be permitted only for those of the frames for which the exposure completed information is not played back, i.e., for the unexposed frames.
It is desirable to use a recording signal of relatively high frequency so as to record the information in the magnetic recording region in as high a density as possible, in order to record as large a quantity of photographic information as possible, for example, in order to record character information input by the camera user as well as the date and/or the time of shooting and the exposure values. However, if such a recording signal of relatively high frequency is used not only for recording the photographic information but also for recording the exposure completed information, the following problems tend to arise.
This type of exposure completed information is played back by the playback device housed in the camera when the film cartridge accommodating a partially used file is reloaded into the camera. The magnetic recording and playback head provided in the camera is subject to inclination of the recording portion (head gap) thereof with respect to the direction of forwarding of the film due to manufacturing variations, and furthermore the angle of this inclination (azimuth angle) is not guaranteed to be constant for each camera.
If the unexposed frames of the partially used cartridge are exposed with the same camera by which the film has been partially exposed, no great problem arises with regard to ensuring compatibility of the azimuth angle. However, in the case that various frames are exposed and the recordation of information and playback of information are performed by the different cameras, the problem due to the azimuth angles occurs.
Relative deviation may occur between the direction in which the signal has been recorded on the magnetic recording region and the direction of inclination of the recording portion, and so called azimuth loss can occur if the deviation of the azimuth angle is large, so that it may happen that the exposure completed information cannot be read back accurately. In other words with a high frequency recording signal it may undesirably occur that while reading back one portion of the recorded signal a neighboring portion thereof is picked up because the interval between mutually neighboring recorded signal portions is reduced, and for this reason there is a chance that the exposure completed information cannot be properly read back.